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Unformatted text preview: PGE 421K, Spring 2010 HOMEWORK 4 60 points Due M 1 Mar 1. Your steam-soak project in Canada requires 1000 kg/d of saturated steam at P = 50 atm for 30 days. Feed water is available at 35 deg. C and 1 atm. a. How much natural gas will your project require? Total steam requirement = 1000 gG 30 = 3 10 Cumulative energy balance: 30 = 3 10 3 10 50 = 2794 35 = 147 = 3 10 2794 147 = 79.4 10 is the heat required from the burner. = 890 Methane required: = 79.4 10 890 = 89.2 10 = 89.2 b. Suppose the only burner available is set to use 50% more air than the stoichiometric requirement. Will you produce more or less steam than if you used a burned that operated with stoichiometric air? Explain your answer. 20 pts Using twice as much air means we still burn all 89 kgmol of methane. However, some of the heat of reaction will now go to increasing the temperature of the excess air. Thus, we will make less steam. The enthalpy of the heated air is not large compared to the heat of reaction of methane, so the reduction of steam produced would not be large. reaction of methane, so the reduction of steam produced would not be large....
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